Cargo bike as an e-MTB?

Hello everyone,

I'm looking for a bike the size of a mountain bike, but with an extremely sturdy luggage rack.

The reason is that I want to take a second person (50 kg/1.68 cm) with me. Is there a standard-sized bike that would allow this legally?

If it's not entirely legal, at least a bike that's at least conceivable for legal use would be good. It can't be wider or longer than a regular bike, as it has to fit in the motorhome.

Thanks for all the tips and best regards